A deferred which fires when authentication is complete. If successful, it
returns an IMailbox
interface, a mailbox and a logout function. If authentication fails, the
deferred fails with an UnauthorizedLogin
error. (type: Deferred
which successfully results in 3-tuple
of (IMailbox,
IMailbox
provider, no-argument callable))

A deferred which fires when authentication is complete. If successful, it
returns an IMailbox
interface, a mailbox and a logout function. If authentication fails, the
deferred fails with an UnauthorizedLogin
error. (type: Deferred
which successfully results in 3-tuple
of (IMailbox,
IMailbox
provider, no-argument callable))